This invention relates to liquid ring pumps, and more particularly to structures for supporting the rotatable housings of liquid ring pumps having such housings.
Liquid ring pumps with rotatable housings are well known as shown, for example, by such references as Stewart U.S. Pat. No. 1,668,532 and Kollsman U.S. Pat. No. 2,453,375. In such pumps a rotor having a plurality of circumferentially spaced, radially and axially extending blades is disposed in the hollow, annular housing. The rotor rotates about its central longitudinal axis. The rotor axis is parallel to but laterally spaced from the longitudinal axis of the housing. The housing is rotatable about the housing axis. The housing contains a quantity of pumping liquid (usually water). Rotation of the rotor causes the rotor blades to engage the pumping liquid and to form that liquid into a recirculating, hollow annulus or ring inside the housing. Because the rotor is eccentric to the housing, the radially inner surface of the liquid ring between any two circumferentially adjacent rotor blades alternately moves toward and away from the rotor axis as the rotor rotates. Where the inner surface of the liquid ring is moving away from the rotor axis, the pump can pull gas into the expanding volume bounded by the circumferentially adjacent rotor blades and the inner surface of the liquid ring. Where the inner surface of the liquid ring is moving toward the rotor axis, the pump compresses the gas in the contracting volume bounded by the adjacent rotor blades and the inner surface of the liquid ring. Gas is admitted to the pump where the above-mentioned volumes or pumping chambers are expanding. Compressed gas is discharged from the pump where the above-mentioned volumes or pumping chambers have contracted by the desired amount. A principal reason for providing a rotatable rather than a stationary housing is to reduce fluid friction losses between the rotating liquid and the housing.
As an alternative to a full rotating housing, it is known to provide liquid ring pumps with a stationary housing having a rotating liner inside the housing. Structures of this kind are shown, for example, in German patent 587,533 and in Russian patents 1,035,290, 1,038,583, 1,040,221, and 1,523,727. The rotating liner helps reduce fluid friction losses between the rotating liquid and the housing.
Various means are known for supporting such liners for rotation relative to the housing. For example, it is known to use ball bearings as shown in German patent 587,533 and in Russian patents 1,035,290 and 1,523,727. It is also known to use a liquid bearing as shown, for example, in Haavik U.S. Pat. No. 5,100,300 or a gas bearing as shown in Haavik U.S. Pat. No. 5,295,794.
Each of these types of liner bearing structures may have certain disadvantages in some applications. For example, ball bearings have only a relatively small bearing surface and so tend to cause relatively high stress and high wear rates where they contact the outer surface of the liner unless the liner is made of a relatively expensive, high grade material. Liquid and gas bearings, on the other hand, tend to require a fairly precisely controlled clearance between the liner and the housing. This tends to increase the manufacturing cost of the pump. Such structures may also be somewhat sensitive to any contamination of the liquid or gas bearing medium. The liner may cease to rotate if the bearing medium becomes contaminated.
The known structures for supporting rotating housings also tend to have various disadvantages. The most common types of housing supports are bearings of the type shown in Stewart U.S. Pat. No. 1,668,532 which are axially spaced from the main body of the housing. In general, these bearings are difficult or impossible to service without stopping and substantially disassembling the pump. This is undesirable because in many applications liquid ring pumps are needed to provide uninterrupted service for very long periods of time (e.g., in support of other complex and expensive operations such as papermaking machinery which should not have to be interrupted because the liquid ring pump needs service). Somewhat more unusual rotatable housing support structures are shown in Kollsman U.S. Pat. No. 2,453,375. There the rotatable housing is supported by a flexible belt or by a pair of spaced rollers. Again, however, these support structures are impossible to repair or replace without stopping the pump.
In view of the foregoing, it is an object of this invention to provide improved support structures for the rotating housings of liquid ring pumps.
It is a more particular object of this invention to provide support structures for the rotating housings of liquid ring pumps, which support structures can be more easily maintained (including repair and replacement of various bearing components) without stopping or significantly disassembling the pump.